Allodynia Common in Pediatric Migraine
Central sensitization refers to the hypersensitization to painful stimuli or allodynia.
Symptoms associated with central sensitization are common in children and adolescents with migraine, according to a study recently published in the Journal of Headache and Pain.1 Central sensitization refers to the hypersensitization to painful stimuli or the perception of pain in response to ordinary touch or pressure (allodynia).2 The high prevalence of cutaneous allodynia and pericranial tenderness in adults with migraine is well documented, but their prevalence in pediatric patients is less clear.1,2
The observational study included 150 patients aged 8 to 15 years who visited the neurophysiopathology of pain unit at Bari University, Italy, a tertiary headache center, for confirmed episodic or chronic migraines between January 2013 and June 2015.1 The patients' mothers were instructed to have their child fill out a questionnaire on allodynia as they were experiencing a migraine attack. The investigators used additional questionnaires to determine how migraine attacks affect the participants' disability, mood, and sleep, and evaluated the presence of juvenile fibromyalgia in study participants.
Allodynia was found in 97% of study participants, a higher prevalence than that observed in adult patients with migraine (estimated at 70% to 80%).2 The number of children without aura in the study was too small (n=12) to draw meaningful conclusions regarding the relationship between aura and allodynia. No significant difference was found in the prevalence of allodynia between children with a diagnosis of episodic vs chronic migraine. Severe allodynia was associated with a worse overall score for clinical symptoms. Specifically, more severe allodynia scores corresponded with significantly higher scores for anxiety and pain catastrophizing.
In 68.38% of children, pericranial tenderness co-occurred with migraine attacks. According to the authors, pericranial tenderness "is a sign of persistent activation of the trigeminal and cervical nociceptors." Pericranial tenderness was more intense in children with chronic vs episodic migraine (P <.0009), and was associated with shorter sleep duration (P =.048), but not with greater disability.
Only 5 pediatric migraine patients (0.03%) were found to have juvenile fibromyalgia. Children with comorbid juvenile fibromyalgia had more severe allodynia (P =.037) and pericranial tenderness (P =.004) and a higher risk for depression (P =.0003). A fibromyalgia diagnosis was also associated with worse quality of life.
According to the researchers, these results confirm the notion that allodynia is a common symptom of childhood migraine and may significantly contribute to migraine-related disability. "Psychiatric comorbidity seems to have a major role in central sensitization at this age," they wrote, highlighting the relationship between anxiety and allodynia. The researchers also recommended routine assessment of children with migraine for central sensitization symptoms.
Summary and Clinical Applicability
The high prevalence of central sensitization symptoms such as allodynia and pericranial tenderness in pediatric patients with migraine, combined with the relationship between central sensitization symptoms and worse clinical outcomes, emphasizes the need for routine assessment of central sensitization symptoms in this patient population.
- The study was conducted in a single institution.
- The instrument used to assess allodynia was developed for adults, not children.
- It is not clear how having the mother administering the allodynia questionnaire might have affected results.
- The large variability in symptoms by patient age suggests the need for studies that include larger populations in each age group. Larger studies are also needed to assess the relationship between migraine and juvenile fibromyalgia.
- Tommaso de M, Sciruicchio V, Delussi M, et al. Symptoms of central sensitization and comorbidity for juvenile fibromyalgia in childhood migraine: an observational study in a tertiary headache center. J Headache Pain. 2017;18(1):59. doi: 10.1186/s10194-017-0764-8
- Woolf CJ. Central sensitization: implications for the diagnosis and treatment of pain. Pain. 2011;152(3 Suppl):S2-S15. doi: 10.1016/j.pain.2010.09.030